I was under the impression that 1959 Flight was detached to Henlow at some stage whilst 1957 & 1960 Flights were based at Kenley.
An Appendix to 661 Squadron ORB shows the dispersals to Henlow, Hendon and Kenley early in 1950 (but unfortunately TW577 is not one of the Austers listed) so by 1954 arrangements may well have been amended.